Modular element for a solderless expandable terminal strip

ABSTRACT

A modular element for use in a solderless expandable terminal strip molded from non-conductive material and formed with interlocking tenons and mortises. Each module has a screw seated in a well into which other conductor seating wells converge at an acute angle such that the screw crest assembled in the well cuts through the conductor insulation and into the conductor itself thereby making a firm anchorage as well as multiple electrical contacts therewith.

United;- States Patent [1 1 Clark [4.51 *Nov. 6, 1973 MODULAR ELEMENT FOR A SOLDERLESS EXPANDABLE TERMINAL STRIP [76] inventor: Marvin A. Clark, 7902 Woodley Ave., Van Nuys, Calif. 91406 Notice: The portion of the term of this patent subsequent to May 18, 1988, has been disclaimed.

[22] Filed: Aug. 10, 1971 [21] Appl. No.: 170,494

[52] US. Cl. 339/31 R, 339/98, 339/198 G [51] int. Cl. 1101r 29/00, HOlr 9/08 [58] Field of Search 339/198, 196, 31,

[56] References Cited UNITED STATES PATENTS Meyer 339/198 E 3,579,172 5/1971 Clark 339/97 P 2,726,375 12/1955 Gordon 339/198 G 9/1970 Haag 339/31 M Primary Examiner-Marvin A. Champion Assistant ExaminerWilliam F. Pate, lll

' Att0rneyW. D. Sellers et al.

[57] ABSTRACT A modular element for use in a solderless expandable terminal strip molded from non-conductive material and formed with interlocking tenons and mortises. Each module has a screw seated in a well into which other conductor seating wells converge at an acute angle such that the screw crest assembled in the well cuts through the conductor insulation and into the conductor itself thereby making a firm anchorage as well as multiple electrical contacts therewith.

10 Claims, 5 Drawing Figures MODULAR ELEMENT FOR A SOLDERLESS EXPANDABLE TERMINAL STRIP This invention relates to conductor terminal strips, and more particularly to a novel, readily expandable strip formed of individual modular elements each including a solderless anchorage to one or more electrical conductors.

Many proposals have been made heretofore for terminal strips for anchoring two or more conductors together in a positive and reliable manner. These proposals vary widely in their suitability and practicality for this purpose. Although some of these proposals make provision for expanding the strip capacity, the strips provided for this purpose are subject to various shortcomings and disadvantages avoided by the present invention.

The expandable solderless terminal strip provided by this invention comprises a' one-piece modular element having provision for making a solderless connection with two or more conductors with or without an insulative covering. Each module is molded in one piece from non-conductive material and has a single threaded central well for a conductive screw the crest of the threads of which extends into a plurality of conductor seating wells having their inner ends converging through the sidewall of the central well. Hence, tightening of the single screw cuts through the insulative covering for any or all of the conductors and penetrates into the conductor itself at a plurality of points providing not only a high strength mechanical connection with the conductors but a highly effective electrical connection therebetween. It is unnecessary to remove the insulation from the conductors which are simply cut to length and inserted into the seating well followed by tightening of the anchor screw.

The exterior surfaces of the module include at least one tenon member and one complementally shaped mortise slot mateable with the corresponding tenon of another identical modular element. By this means the strip can be expanded to meet any existing or future requirements as the need arises. A further feature isthe fact that the anchor screws of selected ones of the modules can be interconnected by a connector'co'nductor with the result that any number of conductors. can be connected together by using two or more modular elements having their respective screws connected in series. The screw seating well has parallel sidewalls and its outer end flares to seat the similarly flaring outer end of the screw thereby providing a stop limiting tightening of the screw.

Accordingly, it is a primary object of the present invention to provide an improved and unique modular solderless conductor terminal member for connecting a plurality of insulated or non-insulated conductors together.

Another object of the invention is the provision of an improved modular terminal element for conductors with provision for separably interlocking the same with one or more additional modules to provide a readily expandable terminal strip.

Another object of the invention is the provision of solderless conductor terminal module having a nonconductive main body formed with a threaded central well and a plurality of conductor seating wells converging and intersecting the sidewall of the central well at its inner end and adapted to be interconnected by a conductive screw threaded into the central well.

Another object of the invention is the provision of an expandable terminal strip formed of modular elements and having provision for connecting any desired number of conductors together without limit.

These and other more specific objects will appear upon reading the following specification and claims and upon considering in connection therewith the attached drawing to which they relate.

Referring now to the drawing in which a preferred embodiment of the invention is illustrated:

FIG. 1 is a perspective view of an illustrative embodiment of several of the invention modules joined together with conductors anchored to some of them;

FIG. 2 is a top plan view of one of the modules;

FIG. 3 is a side elevational view of the module shown in FIG. 2 and indicating by dot and dash line the mannot of assembling a second module thereto, portions of the first module being broken away to show constructional details;

FIG. 4 is a cross sectional view taken along the broken line 44 on FIG. 2; and

FIG. 5 is a cross sectional view taken along the line 55 on FIG. 1.

Referring initially more particularly to FIGS. 1 and 5, there is shown several of the invention modular elements 10,10 interlocked with one another. Each module comprises a cubicle block of high strength plastic material molded in the configuration shown and having deep recesses 11,11 opening through the opposed faces thereof and provided with openings 12 at their lower ends to receive anchoring screws to secure the module to a suitable support. Thetwo faces of the module to either side of recesses 11, 11 include a dovetail shape tenon 13 and a complementally shaped mortise 14 contoured to have a close sliding fit with the similarly contoured tenons and mortises of other modules. Although the tenons and mortises 13,14 are here shown as dovetail shape it will be understood that other interlocking contours are equally suitable and may be used.

Each module includes at least one deep threaded well 16 opening through one end surface of the module and having parallel sidewalls. Each well 16 has a coarse thread 18 here shown as of square cross section. This thread mates with a thread 19 of a metallic screw20. Desirably the screw thread is of V-shape in cross section with its outer face lying substantially normal to the axis of the screw and its other face inclined to the screw axis. The sharp hardened crest 22 of thread 19 is effective to cut through conductor insulation as well as to penetrate into even hardened conductor wires without becoming dull or blunted.

Surrounding well 16 are a plurality of smaller diameter wells 25 converging downwardly toward the lower end of central well 16 and opening into the sides of the central well near its inner end. Wells 25 are formed with precision and their inner ends are so positioned that the crest 22 of the screw thread 19 cuts into the conductor at several points along its length. Usually but not necessarily the wells. 25 are designed to receive insulated conductors having eithera single or multiple conductors 27 surrounded with insulation 28. Usually insulation is present and in this case it is important that the lower ends of wells 25 be so arranged that the screw crest 22 cuts through the insulation and then penetrates for a substantial distance into the conductor itself. If insulation is not to be present on the conductors then, of course, the wells are so positioned and proportioned that the screw crest cuts similarly into the conductor as the screw is. fully tightened.

The fully tightened condition of the screw is preferably determined by providing its outer end with an .outwardly flaring surface 30 which seats in a complementally shaped countersunk outer end portion of well 16.

The bottoming of taper surface 30 against this countersink definitely limits the tightening of the screw and provides the operator with an indication that the screw has been fully tightened with the crest of its thread cutting into the conductor at a number of points providing both a positive electrical connection and a firm mechanical anchorage of the conductor in the module.

FIG. 1 shows several conductors completely assembled and anchored in place by the conductive screw 20. This view also shows a connector conductor 35 having its opposite ends extending into a well 25 of adjacent modules 10,10. When so installed the two adjacent modules can be employed to electrically interconnect a total of six conductors. If additional capacity for anchoring more conductors to one another is required then additional connector loops 35 are employed to interconnect additional ones of the module, or, alternatively, the modules include a larger number of wells 25.

As will be appreciated, loops 35 may be usedto interconnect modules widely spaced from one another simply by increasing the length of the connector loop 35. 7

Although modules 10 are here shown as having their interfitting tenons and mortises positioned on diametrically opposed faces of the module, it will be readily apparent that these interlocking components may be provided on adjacent faces if so desired in order that the terminal strip can be located in a corner of a compartment or about an outside corner of some piece of equipment if this should prove desirable for any reason.

While the particular modular element for a solderless expandable terminal strip herein shown and disclosed in detail is fully capable of attaining the objects and providing the advantages hereinbefore stated, it is to be understood that it is merely illustrative of the presently preferred embodiment of the invention and that no limitations are intended to the detail of construction ordesign herein shown other than as defined in the appended claims.

I claim:

1. A modular element for use in a solderless expandable terminal strip comprising a homogenous block of non-conductive material having a tenon formed in one face and a complementally shaped mortise in a second face thereof each adapted to have an interlocking fit with a similar mortise and tenon respectively of another modular element, said modular element having a threaded well opening through a third face thereof, a plurality of non-threaded wells opening through said third face closely adjacent the rim of said threaded well with their axes converging toward the axis of said i threaded well at an acute angle, said non-threaded wells being sized to have a close fit with a conductor and the inner ends of said wells opening through the sidewall of said threaded well, and a conductive screw having a hardened sharp-crested thread seated in said threaded well and effective as it is advanced thereinto to have the crest of its thread penetrate into one or more conductors inserted into said non-threaded wells and effective to anchor said conductor therein and to make a highly effective electrical contact therewith at a plurality of points.

2. A modular element as defined in claim 1 characterized in that said threaded well has parallel sidewalls.

3. A modular element as defined in claim 1 characterized in that said threaded well is substantially deeper than the length of said screw, and said screw having a kerfed head the end surface of which lies below the third face of said block when said screw is tightened against a conductor.

4. A modular element as defined in claim 3 characterized in that the shank of said screw flares to the diameter of the crest of the thread formed therealong to providea flaring head for the screw, and the outer end portion of -said threaded well being flared complementally to the flare on the screw head and cooperating therewith to limit tightening of the screw.

5. A modular element as defined in claim 1 characterized in that said tenon and mortise are disposed on the opposed faces of said block.

6. A modular element as defined in claim 5 characterized in that said tenon and mortise extend from edge to edge of said first and second block faces.

7. A modular element as defined in claim 1 characterized in that said block is molded in one piece from high strength plastic material.

8. A modular element as defined in claim 1 characterized in that said block includes at least one opening to receive a fastener for securing said block to a support.

9. A modular element as defined in claim 1 characterized in that said screw thread projects into said nonthreaded .wells sufficiently to pass through insulation covering a conductor and to penetrate into the conductor itself at a plurality of points whereby it is unnecessary to remove the conductor insulation to provide electrical contact with said screw as it is tightened.

10. A modular element as defined in claim 1 characterized in being interlocked with a plurality of identical modular elements along at least one of said first and second faces, and means for securing said interlocked modular elements to a common support juxtaposed to a fourth face of said modular elements. 

1. A modular element for use in a solderless expandable terminal strip comprising a homogenous block of non-conductive material having a tenon formed in one face and a complementally shaped mortise in a second face thereof each adapted to have an interlocking fit with a similar mortise and tenon respectively of another modular element, said modular element having a threaded well opening through a third face thereof, a plurality of nonthreaded wells opening through said third face closely adjacent the rim of said threaded well with their axes converging toward the axis of said threaded well at an acute angle, said nonthreaded wells being sized to have a close fit with a conductor and the inner ends of said wells opening through the sidewall of said threaded well, and a conductive screw having a hardened sharp-crested thread seated in said threaded well and effective as it is advanced thereinto to have the crest of its thread penetrate into one or more conductors inserted into said nonthreaded wells and effective to anchor said conductor therein and to make a highly effective electrical contact therewith at a plurality of points.
 2. A modular element as defined in claim 1 characterized in that said threaded well has parallel sidewalls.
 3. A modular element as defined in claim 1 characterized in that said threaded well is substantially deeper than the length of said screw, and said screw having a kerfed head the end surface of which lies below the third face of said block when said screw is tightened against a conductor.
 4. A modular element as defined in claim 3 characterized in that the shank of said screw flares to the diameter of the crest of the thread formed therealong to provide a flaring head for the screw, and the outer end portion of said threaded well being flared complementally to the flare on the screw head and cooperating therewith to limit tightening of the screw.
 5. A modular element as defined in claim 1 characterized in that said tenon and mortise are disposed on the opposed faces of said block.
 6. A modular element as defined in claim 5 characterized in that said tenon and mortise extend from edge to edge of said first and second block faces.
 7. A modular element as defined in claim 1 characterized in that said block is molded in one piece from high strength plastic material.
 8. A modular element as defined in claim 1 characterized in that said block includes at least one opening to receive a fastener for securing said block to a support.
 9. A modular element as defined in claim 1 characterized in that said screw thread projects into said non-threaded wells sufficiently to pass through insulation covering a conductor and to penetrate into the conductor itself at a plurality of points whereby it is unnecessary to remove the conductor insulation to provide electrical contact with said screw as it is tightened.
 10. A modular element as defined in claim 1 characterized in being interlocked with a plurality of identical modular elements along at least one of said first and second faces, and means for securing said interlocked modular elements to a common support juxtaposed to a fourth face of said modular elements. 